The present invention generally relates to a method and composition for enhancing the concentration of oleic acid in milk produced by ruminants. More particularly, the present invention relates to a feed composition that includes oilseed high in oleic acid content and to a method of using this feed composition to enhance the oleic acid content of milk produced by ruminants. Furthermore, the present invention relates to butter that is based upon milk produced by ruminants that are fed oilseed high in oleic acid.
It is generally known that feed compositions for ruminants may be manipulated to effect changes in the composition of milk produced by lactating ruminants. Considerable effort has been directed to modifying ruminant feeding regimens to enhance the concentration of oleic acid in milk produced by ruminants. Saturated fatty acids in milk and dairy products that are based upon milk contribute to adverse health effects, such as coronary heart disease and high blood pressure in humans. However, mono-unsaturated fatty acids, such as oleic acid, are believed to be nutritionally more favorable for the human diet. In addition, mono-unsaturated fatty acids, such as oleic acid, are more stable against oxidation than some other fatty acids and thereby reduce the tendencies of dairy products to become rancid.
The challenge is to create a feed material that is both high in oleic acid content and that, when orally fed to lactating ruminants, supports transfer of most, if not all, of the oleic acid content from the feed material to milk produced by the ruminant. A number of prior efforts have been directed at resolving this dilemma. Some have attempted to directly feed ruminants feed materials containing increased amounts or concentrations of unsaturated fatty acids, such as oleic acid. However, it has been determined that if the proportion of fat in the diet of cattle exceeds about five weight percent of the total feed, the fat has toxic effects upon microorganisms in the rumen of the ruminants. It appears that fat reduces the growth rate, or even kills, certain microorganisms which digest fiber in the rumen, thereby lowering fiber digestibility. Furthermore, it is known that triglycerides and free fatty acids can physically coat fibrous or cellulosic material in the rumen and inhibit fermentation of the fibrous or cellulosic material by the microorganisms in the rumen. This has an adverse effect on the total digestibility of the diet and has been found to at least sometimes reduce the yield of milk and milk fat by ruminants.
Other efforts directed toward increasing oleic acid content and concentration in milk produced by ruminants rely on coating or chemically altering lipids to make the lipids rumen-inert. For example, transformation of lipids to the calcium salt form has been attempted. However, calcium salts of lipids have been found to be unpalatable, at least to some ruminants. Thus, use of calcium salt forms of lipids may cause a net reduction in feed intake and thereby negatively effect milk production rates and milk fat production rates by ruminants. Still others have proposed treatment of oil-bearing substances, or even oilseeds, with formaldehyde to render the lipids contained therein rumen-inert. However, there are health concerns relating to this use of formaldehyde. Furthermore, formaldehyde is not approved by the United States Food and Drug Administration for this type of application in animal feeds.
Another approach involves feeding untreated sunflower seeds containing high concentrations of oleic acid. These seeds were administered in the untreated form, without being rendered rumen-inert, since saturated and monosaturated fats are believed to be less toxic to rumen microorganisms than polyunsaturated fats, and thus less likely to interfere with microorganism activity and, consequently, fiber digestibility in the rumen. However, these efforts were not entirely satisfactory, since the high oleic acid sunflower seed feeding regimen caused a reduction in the concentration of fat in milk produced by the ruminants, caused a reduction in the concentration of total solids in the milk produced by the ruminants, and caused a reduction in the dry matter intake by the ruminants.
Though the various ruminant feeding techniques that have been proposed and/or practiced over the years have enhanced the overall knowledge base with respect to ruminant feeding, these techniques have not adequately addressed the problem of how to most economically, efficiently, and effectively maximize the transfer of oleic acid to milk produced by ruminants, without adversely effecting ruminant feed intake and ruminant health and digestion. Therefore, a need still exists for an improved method and composition for feeding ruminants that enhances the transfer of oleic acid from the feed to milk produced by the ruminant, that enhances the overall concentration of milk fat in the milk produced ruminant, and that enhances the total solids content of milk produced by the ruminants. The method and composition of the present invention meets this unfulfilled need.